From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id AB64CC43458 for ; Wed, 1 Jul 2026 06:11:22 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7C0E36B00A8; Wed, 1 Jul 2026 02:11:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7720D6B00A9; Wed, 1 Jul 2026 02:11:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 688586B00AB; Wed, 1 Jul 2026 02:11:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 2C2A96B00A8 for ; Wed, 1 Jul 2026 02:11:21 -0400 (EDT) Received: from smtpin14.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 8D9D01A0248 for ; Wed, 1 Jul 2026 06:11:20 +0000 (UTC) X-FDA: 84939185520.14.DC958A9 Received: from out-174.mta1.migadu.com (out-174.mta1.migadu.com [95.215.58.174]) by imf06.hostedemail.com (Postfix) with ESMTP id 7B3CF180002 for ; Wed, 1 Jul 2026 06:11:18 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=bkjg0hSE; spf=pass (imf06.hostedemail.com: domain of ye.liu@linux.dev designates 95.215.58.174 as permitted sender) smtp.mailfrom=ye.liu@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1782886279; b=pT851OIXkTRGTbywaoqlHx6s23UvMVL6rEwwDPuwcccMRVZ7ktSwWURXXTUbu6bQdptGP/ 3nWSBgCeCqe6qbxLOgAvlAWh22wxO7JVZPzicGCAZ/TZQ8q4ytNKkMbAom8GX8BsbGLHFJ CZiARPxkeFhDPQaeyDdwI6mEMtF7Un4= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1782886279; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=JMExFnjyQtVXN7x+iPdJHV2C/UohwacNGTdpQ/luPkA=; b=aSZgRRU6NDyVvcS7hpU825AGWAMXaXTnVScuH2BIeuFLt3FfZ9MMdxLgwtV1lTwrxW5esl waiOqWXnJkoVhtf+MxKtwDozlGdLdwdePlPCsZj1lGkxCDJhiU6WQJKA30kquUmXv20HEQ bLgnie00oC7R8d4VwQkpGlrIYl7gnqs= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=bkjg0hSE; spf=pass (imf06.hostedemail.com: domain of ye.liu@linux.dev designates 95.215.58.174 as permitted sender) smtp.mailfrom=ye.liu@linux.dev; dmarc=pass (policy=none) header.from=linux.dev X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1782886277; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JMExFnjyQtVXN7x+iPdJHV2C/UohwacNGTdpQ/luPkA=; b=bkjg0hSEnefr0xknPnvIvmFhT4Naamc6EL9eaEQkfQ9ep6vorBu7I12mkJ2rqzZA8em9rO D9AP612nucjzD8A32qdJMSVsCqqou+p7M2w4aMYrpuHS0VP9xUotWqx94z0L50QQARRtTP FNM09wdxp2NGTOtZvewELxz4HZy1dS8= From: Ye Liu To: Andrew Morton , Vlastimil Babka Cc: Ye Liu , Zi Yan , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 1/9] mm/page_owner: extract skip_buddy_pages() helper to unify buddy page skipping Date: Wed, 1 Jul 2026 14:10:44 +0800 Message-ID: <20260701061101.344679-2-ye.liu@linux.dev> In-Reply-To: <20260701061101.344679-1-ye.liu@linux.dev> References: <20260701061101.344679-1-ye.liu@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 7B3CF180002 X-Stat-Signature: 3j5phrofugp149u9k1skeyywm3hxqp9b X-HE-Tag: 1782886278-345447 X-HE-Meta: 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 Qrzb0jWg hk8ebAvgJCIAgubE27n+TFGi54MXBaSY0SM2Ja5dt2kZnzlmW8y9g9m79JQh0wp2GhXgX5TvUjJacGmI8hK03AqsiHoSLJfo5q4eRDkG67SBunQSGopdPa9356DuPEnQdV5opNACLguXiWq6osUmNq1dlGHp36UAhStFohE22iB16O+/ItGov0zZ9KZjqEakTzkf6zCI3NJgxZAV6+3C0QmIhNnjkrSgqMAW/GiVn02OxXUvA6rbG6rNOEdh1jrvhpR7UTTtQj1uFg2sf0zV+2SDHV8zWDZmCMhq8B4GxOBM15O8= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Three places in page_owner.c duplicate the same pattern: check if a page is PageBuddy, read its order via buddy_order_unsafe(), advance the pfn past the buddy block if the order is valid, and continue. Consolidate them into a single inline helper skip_buddy_pages(). The function returns true (skip) for any buddy page and advances @pfn past the block when the order is valid; returns false if the page is not a buddy page and should be processed normally. The old init_pages_in_zone() variant used "order > 0" as an extra guard before advancing pfn, but the continue was unconditional and (1UL << 0) - 1 == 0, so the behaviour is identical. The comment about zone->lock is preserved in the helper's kernel-doc. No functional change. Signed-off-by: Ye Liu Reviewed-by: Zi Yan Reviewed-by: Vlastimil Babka (SUSE) --- mm/page_owner.c | 52 ++++++++++++++++++++++++------------------------- 1 file changed, 26 insertions(+), 26 deletions(-) diff --git a/mm/page_owner.c b/mm/page_owner.c index 2dddcb6510aa..342549891a8d 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -422,6 +422,29 @@ void __folio_copy_owner(struct folio *newfolio, struct folio *old) rcu_read_unlock(); } +/* + * Check if a page is a buddy page and advance @pfn past the entire buddy block. + * This safely reads the buddy order without the zone lock, which may cause us + * to skip less than the full buddy block, but that is acceptable for page owner + * iteration purposes. + * + * Return: true if the page was skipped (caller should continue its loop), + * false if the page is not a buddy page and should be processed normally. + */ +static inline bool skip_buddy_pages(unsigned long *pfn, struct page *page) +{ + unsigned long order; + + if (!PageBuddy(page)) + return false; + + order = buddy_order_unsafe(page); + if (order <= MAX_PAGE_ORDER) + *pfn += (1UL << order) - 1; + + return true; +} + void pagetypeinfo_showmixedcount_print(struct seq_file *m, pg_data_t *pgdat, struct zone *zone) { @@ -461,14 +484,8 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m, if (page_zone(page) != zone) continue; - if (PageBuddy(page)) { - unsigned long freepage_order; - - freepage_order = buddy_order_unsafe(page); - if (freepage_order <= MAX_PAGE_ORDER) - pfn += (1UL << freepage_order) - 1; + if (skip_buddy_pages(&pfn, page)) continue; - } if (PageReserved(page)) continue; @@ -697,13 +714,8 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) } page = pfn_to_page(pfn); - if (PageBuddy(page)) { - unsigned long freepage_order = buddy_order_unsafe(page); - - if (freepage_order <= MAX_PAGE_ORDER) - pfn += (1UL << freepage_order) - 1; + if (skip_buddy_pages(&pfn, page)) continue; - } page_ext = page_ext_get(page); if (unlikely(!page_ext)) @@ -798,20 +810,8 @@ static void init_pages_in_zone(struct zone *zone) if (page_zone(page) != zone) continue; - /* - * To avoid having to grab zone->lock, be a little - * careful when reading buddy page order. The only - * danger is that we skip too much and potentially miss - * some early allocated pages, which is better than - * heavy lock contention. - */ - if (PageBuddy(page)) { - unsigned long order = buddy_order_unsafe(page); - - if (order > 0 && order <= MAX_PAGE_ORDER) - pfn += (1UL << order) - 1; + if (skip_buddy_pages(&pfn, page)) continue; - } if (PageReserved(page)) continue; -- 2.43.0